We demonstrated a simple and effective modification of graphene oxide (GO) to enhance the device performance of perovskite photovoltaics. The surface chemistry and morphology of GO was tailored by irradiating aqueous GO solution with 60Co γ-ray. During the irradiation, hydroxyl radicals were believed to be released from water radiolysis and oxidized the surface of pristine GO sheets, supposedly. Furthermore, large GO agglomerates scattered as individual GO sheets with small lateral dimensions, which is advantageous to uniform distribution of GO sheets in PEDOT:PSS layer. PEDOT:PSS layer with γ-ray irradiated GO (γ-GO) facilitated efficient hole transport properties in perovskite solar cells. PEDOT:PSS layer became more hydrophobic by embedding γ-GO after thermal annealing and thus improved the crystallinity of perovskite layer on top of the PEDOT:PSS. Consequently, embedding γ-GO in PEDOT:PSS layer resulted in better electrical properties than PEDOT:PSS layer without GO or with pristine GO. As a result, power conversion efficiency was improved owing to increased charge generation/extraction, and photoluminescence in the perovskite photoactive layer.
Bibliographical noteFunding Information:
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) , funded by the Ministry of Science, ICT and Future Planning ( 2017R1A1A1A05000772 and 2015M2A2A6A01045277 ).
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